a = [0,1,2,2,2,3,4,4,5,5,5,6,7,7,8,9,9]

ruler = 3
print(a)
j = 0

for i in range(len(a)):
    if a[i] >= ruler:
        print(a[j:i])
        ruler = ruler + 3
        j = i

print(a[j:])